Changes in nucleosome repeat lengths precede replication in the early replicating metallothionein II gene region of cells synchronized in early S phase

Journal Article · Tue Apr 04 04:00:00 EDT 1989 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00433a022· OSTI ID:5672889

D'Anna, J A; Tobey, R A ^[1]

---

1. Los Alamos National Lab., NM (USA)

Previous investigations showed that inhibition of DNA synthesis by hydroxyurea, aphidicolin, or 5-fluorodeoxyuridine produced large changes in the composition and nucleosome repeat lengths of bulk chromatin. There the authors report results of investigations to determine whether the changes in nucleosome repeat lengths might be localized in the initiated replicons, as postulated. In most experiments, Chinese hamster (line CHO) cells were synchronized in G1, or they were synchronized in early S phase by allowing G1 cells to enter S phase in medium containing 1 mM hydroxyurea or 5 {mu}g mL{sup {minus}1} aphidicolin, a procedure believed to produce an accumulation of initiated replicons that arise from normally early replicating DNA. Measurements of nucleosome repeat lengths of bulk chromatin, the early replicating unexpressed metallothionein II (MTII) gene region, and a later replicating repeated sequence indicate that the changes in repeat lengths occur preferentially in the early replicating MTII gene region as G1 cells enter and become synchronized in early S phase. During that time, the MTII gene region is not replicated nor is there any evidence for induction of MTII messenger RNA. Thus, the results are consistent with the hypothesis that changes in chromatin structure occur preferentially in the early replicating (presumably initiated) replicons at initiation or that changes in chromatin structure can precede replication during inhibition of DNA synthesis. The shortened repeat lengths that precede MTII replication are, potentially, reversible, because they become elongated when the synchronized early S-phase cells are released to resume cell cycle progression.

• OSTI ID: 5672889
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 28:7; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMIDES
ANIMAL CELLS
CELL CULTURES
CELL CYCLE
CELL DIVISION
CHO CELLS
CHROMATIN
DNA REPLICATION
GENES
HYBRIDIZATION
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
HYDROXYUREA
MESSENGER-RNA
METALLOPROTEINS
METALLOTHIONEIN
MITOSIS
MOLECULAR BIOLOGY
MOLECULAR STRUCTURE
NUCLEIC ACID REPLICATION
NUCLEIC ACIDS
NUCLEOSOMES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PROTEINS
RNA
SYNCHRONOUS CULTURES
TRITIUM COMPOUNDS